How to solve a nested summation with recursive function?

Hi,

I have a question related to solving a nested summation equation with a recursive function.

Suppose I have an equation of:

So, I tried to solve this problem by using a for loop to solve the summation equation and using a recursive function to expand the order of nested summation.

 test(3,0)

 function [sum] = test(a,b)

 sum = 0;

 for i=1:a-b

    if a-b == 1
        sum = 1;
    else
        sum = sum + (a-b) * test(a,b+i);
    end
 end

 end

From the code I got

 ans = 9

I appreciate any help, thanks.

Answer 1

[Matt J]

I think your code is correct, and your calculation by hand is not.

[Irvanda Kurniadi Virdaus]

Ah you are right, I think I messed up the break down on the second nested sum.

It should be:

3(2+0)+3(1)+3(0)=9

Thanks for correcting